Why don't muslims help each other?
They do.
And Muslims and Christians reach out and help each other in Gaza, too.
Here is an excerpt of an article about this, people in Gaza reaching out and helping each other after Cast Lead.
GOD GIVES YOU strength, says Araxi Waheed, recalling the terror she felt alone on a night when a dozen Israeli missiles pounded her neighborhood. Waheed, a widow and one of about 3,000 Christians among Gazas 1.7 million residents, is a board member of the Near East Council of Churches Committee for Refugee Work (NECCCRW).
In the weeks following the attacks, she and her Muslim neighbors helped each other endure shortages of food, water, and electricity resulting from Israels targeting of civilian infrastructure.Like Waheed, the committee answers Christs call to love ones neighbors, offering medical clinics and vocational schools to meet the needs of Gazas most vulnerable. By serving their neighbors without discrimination, the committee enjoys the respect of the Muslim majority, though in rare cases Islamist extremists have targeted other Christians. One of their clinics was destroyed by Israeli bombs, but it has since been rebuilt and continues to serve the community.
Gaza: The Persistent Paradox - Ryan Rodrick Beiler | Sojourners Magazine - September-October 2013